Summary: acpi: Add an interface to obtain DSM information
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Authored by bwidawsk on Sep 11 2018, 6:22 PM.

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Reviewers

kib
jhb

Commits

rS344111: MFC r339577:
rS339577: acpi: Add an interface to obtain DSM information

Summary

The Device Specific Method (_DSM) is on optional object that defines
device specific controls. This will be useful for our power management
controller in upcoming patches. More information can be found in ACPI
spec 6.2 section 9.1.1

https://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf

I've had this sitting in my branch for emulated S3 for quite a while. It works
well there and upcoming devices such as NVDIMM may need this before I am ready
to submit my branch for review.

Test Plan

Tested in my s0ix branch

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Lint Not Applicable

Unit

Tests Not Applicable

Event Timeline

bwidawsk created this revision.Sep 11 2018, 6:22 PM

Harbormaster completed remote builds in B19527: Diff 47920.Sep 11 2018, 6:22 PM

Here is some sample usage from the SPMC driver which will later be up for review:

	dsm_bits = acpi_DSMQuery(acpi_get_handle(dev), lps0_uuid, SPMC_REVISION);
	if ((dsm_bits & 1) == 0) {
		device_printf(dev, "Useless device without _DSM\n");
		return (ENODEV);
	}

	status = acpi_EvaluateDSM(handle, lps0_uuid, SPMC_REVISION,
	    LPS0_DEVICE_CONSTRAINTS, &buf);
 	if (ACPI_FAILURE(status))
		return (ENXIO);

kib added inline comments.Sep 12 2018, 8:31 PM

sys/dev/acpica/acpi.c
2577 ↗	(On Diff #47920)	9.1.1 ?
2587 ↗	(On Diff #47920)	Style(9) prefers to avoid initialization in declaration.
2593 ↗	(On Diff #47920)	return (0);
2638 ↗	(On Diff #47920)	Might be, pass PACKAGE as an arg to acpi_EvaluateDSM() ?
2644 ↗	(On Diff #47920)	to use ?
2659 ↗	(On Diff #47920)	I do not quite understand this comparision.

bwidawsk planned changes to this revision.Sep 13 2018, 6:38 PM

bwidawsk marked 5 inline comments as done.

bwidawsk added inline comments.

sys/dev/acpica/acpi.c
2577 ↗	(On Diff #47920)	It was the correct section for the wrong version of the spec :-)
2638 ↗	(On Diff #47920)	That's fine with me. I was planning to wait until there was actually a user of it. For my usage, it's always just empty, and I just looked now and saw NVDIMM does have some uses for it.
2659 ↗	(On Diff #47920)	I can't remember what I was trying to do here but it doesn't make sense in its current form. I also don't ever expect out_buf to be NULL, so I've changed that as well.

Addressed kib's comments.

Harbormaster completed remote builds in B19574: Diff 48013.Sep 13 2018, 6:40 PM

kib accepted this revision.Sep 13 2018, 7:47 PM

kib added inline comments.

sys/dev/acpica/acpi.c
2616 ↗	(On Diff #48013)	One more return ();
2662 ↗	(On Diff #48013)	And there.
2577 ↗	(On Diff #47920)	Perhaps mention the version in the comment then ?